It's so Easy to Fall in Love with You
by AnneAquila
Summary: Ai thought he was being paranoid at first, but when he caught Yamazaki senpai's disapproving frown during one of Momo's many flying-tackle-bear-hugs that he reserved specially for Rin, Ai knew that he had been right in his suspicions. Momo was being more touchy-feely with Rin senpai. And Ai didn't like it. Not one bit. (Yes, this is a Rin Harem story - everyone loves Rin!)
1. Chapter 1: Observations

**A/N:** Hey guys! It's Aquila here again with another Rin Harem fic! This one's just going to be a whole lot of fluff, fun and feels. No dark stuff here. (But is that's your thing, do check out 'Lay Me By Your Side'!)

I don't really know how this fic is going to pan out, I love all these ships on some level...so it's gonna be up to you guys to tell me what ships you want to see sail! I do have a skeletal plot in mind, though.

Hope you enjoy this, and please hit me up in the comments!

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 **Chapter 1: Observations**

Ai crept quietly down the corridor, listening intently for any unusual sounds. Most of the doors were closed, a few were a open a crack to let slanting bands of sunlight fall in strips across the floor. Nearly all the rooms were empty, as most of the student populous were out enjoying the surprising spell of good weather before the storms set in.

It was hot, Ai realized. Very hot. Beads of perspiration dripped down his forehead as he skulked in the shadows of the dormitory corridor. He could hear light snores snuffling out of the door next to him. Tiptoeing past the room like a ninja, Ai quickly slipped into his dorm which Momo had forgot to lock again. For once, Ai was thankful.

Once inside his room, he breathed a huge sigh of relief. He locked the door shut behind him before ridding himself of his blazer and tossing it carelessly on his desk chair.

The room was a pigsty, as usual. Ai felt a loom of despair weigh on him. He kept on making promises to clean up, but could never get round to doing it. Momo was even messier that he was; leaving behind a constant trail of sweet wrappers, wet soil, dead flies and the remains of his beastly bug collection.

The entirety of the window sill had been taken up by Momo's creepy crawlies. They were housed in various containers – the water beetles in the old goldfish bowl, the millipedes in the discarded conical flask from the chemistry lab, the stick insects in the chipped mug with its handle missing, the ladybirds and fire ants in several tiny jam jars, Pyuunsuke in his dented biscuit tin and a cracked ornamental vase for the butterfly pupae. Copious amounts of leaf litter and soil were also deposited around the room, encouraging more insects to come in from the garden.

Dirty clothes lay strewn across the floor, creating a patchwork carpet for the many stacks of books, magazines and general clutter that seemed to follow Ai around wherever he went. His desk was a lost cause, overflowing with textbooks, study guides, stationary and loose sheets of paper. Momo's desk was little better. Instead of school books, there were sandwich crusts, glow-in-the-dark bubblegum drops, sticks of charcoal, expensive drawing pencils, empty baby food jars, pretty pebbles collected from the grounds, twigs, dry leaves, disposable chopsticks, interesting articles cut out from newspapers, neon colored ink and piles and piles of manga.

The only serious looking book was a bulging volume bound in dark blue leather titled 'An Introduction to Entomology'. The English title was scary enough, but Ai had been well and truly intimidated when he had tried to go through the first few chapters. The text was tiny and densely packed together with almost no paragraphs. It was full of words that made no sense to him at all, making his eyes water and his head feel dizzy after skimming just 2 pages. The only relief was that there were diagrams in the book too, delicately penciled and labeled with more words that Ai couldn't pronounce or fathom. There was an index at the end with hundreds of columns. Ai couldn't make head or tail of the lists, but it looked like Momo could, seeing that he had made tiny notes in the margins and even bookmarked particular pages with his neon colored post its.

Apparently, there was more to Momo than met the eye.

He hadn't been able to be messy when he had bunked with Rin in their old room. His beloved senpai had been a meticulous germophobe and an absolute clean freak. If Yamazaki senpai's glowers were to believed after encountering him in the laundry den at 2 in the morning on more than one occasion, that particular trait hadn't changed.

A fond smile came to his face when he thought about his old room, along with a pang of loss. He remembered Rin senpai in his blue apron (an apron that Rin constantly argued was Gou's, but Ai knew better) armed with his germ annihilating apparatus. Rin hated things that were unclean or soiled, and claimed that neat surroundings led to a an organized mind. Ai had tried to take the words to heart, but old habits die hard and his senpai usually ended up cleaning his messes after him. Dusting the shelves, sweeping away the crumbs left by Ai's late night cravings for mochi, restacking books in alphabetical order, taking out the dirty laundry and ironing all the bed sheets and pillow cases in the linen cupboard. The cleaning missions always ended with the lemon and orchid house freshener, which Rin sprayed all around the room in liberal quantities. It was a smell that Ai associated with Rin, along with the familiar scents of cherry blossom shower gel, Rose and Tulip Cologne, chlorine water, Darjeeling tea, damp soil and fresh air.

Looking around his present room, Ai found himself acutely missing Rin's presence. Momo was difficult to deal with on the best of days, but downright impossible on most. He was hyperactive and could never sit still, tapping his fingers or knocking his knees while Ai tried to study, and he had the attention span of a flea. He was impulsive and painfully blunt with his ideas and thoughts. He also had no concept of personal space, especially with Rin senpai.

Ai thought he was being paranoid at first, but when he caught Yamazaki senpai's disapproving frown during one of Momo's many flying-tackle-bear-hugs that he reserved specially for Rin, Ai knew that he had been right in his suspicions. Momo was being more touchy-feely with Rin senpai.

And Ai didn't like it.

Not one bit.

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 **A/N:** ...And that's Chapter 1. A little shorter than my usual, but I feel it's more effective this way. So, penny for your thoughts? Read and Review!


	2. Chapter 2: Annoyances

**A/N:** Hey guys! Here's the next chapter. Please let me know what you think in the reviews!

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 **Chapter 2: Annoyances**

'Rin senpai! Help me!'

It was 11:30 pm, and Sousuke wanted to sleep.

'Rin senpai, please!'

A flurry of knocks.

Sousuke closed his eyes, trying hard to catch the vestiges of sleep that had set in before the screaming and knocking.

BAM. BAM. BAM.

'Rin senpai, are you in there?'

Sousuke finally got up. The voice was reverberating in his amygdala and drilling into the back of his head like a persistent mosquito. He was afraid that the door would splinter and buckle in on its hinges if he didn't open it soon. He clambered down the ladder, trying to muster a look that could kill when the bathroom door opened.

Rin stumbled out of the shower practically drowning in a giant black tee that was dangerously close to slipping off one shoulder, exposing a smooth unblemished patch of skin the color of milk and ivory and the sharp edge of a clavicle. He had a white fluffy towel wrapped around his waist, and his hair was wet and darkened to a rich shade of carmine. The one strand of hair that stubbornly fell in front of eyes was pinned back with a black barrette.

Sousuke tried not to stare, he really did.

It didn't work.

He suddenly realized why the tee looked so familiar. It was his sleep shirt, the one that he had left on the towel rack.

Rin glanced blearily around the room, another strand of hair falling over his face. Sousuke smiled gently. He'd probably fallen asleep in the shower again.

'The fuck is that, Sou?' Rin's voice was soft with sleep, carrying none of it's usual bite.

BAM. BAM. BAM.

'RIN SENPAI!'

Rin blinked confusedly while Sousuke grit his teeth and stalked to the door. He threw the door open to come face to face with a deranged Momo, carrying a pile of what looked like textbooks and worksheets.

Several doors had already opened down the corridor, and grumpy students were peering out to find out the source of the commotion.

Not wanting to cause more of a scene, Sousuke grabbed Momo and pulled him bodily into the room before slamming the door and locking it behind him.

Momo looked frazzled. His hair was more disheveled than usual and his eyes were bright with panic. He clenched and unclenched his grip on his math textbook before looking at him guiltily.

'Sorry, Yamazaki senpai. I didn't mean to wake you. I just wanted to see Rin senpai about-'

Sousuke cut in with a voice as cold as ice and glare to match.

'Rin can't see anything now. He's tired and needs to sleep. You have a test tomorrow, and it's 11:40 already. Explain what you're trying to accomplish by trying to break open our door.'

'Sou?'

Rin stumbled to Sousuke, feeling terribly tired. He just wanted to curl up and go to sleep.

'What's Momo doing here?' he murmured sleepily, trying to get his brain to wake up a little.

Momo, the little bastard, seized the opportunity to shove his books into Rin's lap and plead at the top of his voice.

'Please senpai, you have to help me! I've got a math test tomorrow and I don't know anything, and it's relations and functions and it's really HARD! And I don't know anything and I'm going to FAIL, and probably get kicked off the swim team 'cause this accounts for a fourth of my grade, and I might get detained and not graduate and never be able to get a job and I'll end up scrubbing drainpipes somewhere and there'll be no one to look after Pyuunsuke and Senpai, you've got to help me! Please!'

By the time he was done, Momo was a blubbering mess.

Rin sighed. He glanced at Sousuke, who looked like he was going to murder someone.

'Inside voice, Momo. You'll disturb the others.'

He sighed again and rubbed his eyes wearily, the sleeve of Sousuke's tee losing the battle and slipping off his shoulder completely.

Frazzled as Momo was, he couldn't ignore what was right in front of him. He stared as the tee slipped further, revealing inches of alabaster skin, untouched, unmarked and so very pure. A flush rose unbidden to his face as his senpai yawned and rubbed his eyes again. Just when did Rin senpai become so beautiful? His throat suddenly felt dry.

'Hey Sousuke, go back to bed. I'll take care of this.'

Rin picked up the math textbook and began leafing through the pages.

'Rin, it's late. You need to sleep. Momo can manage on his own.'

'It's ok, it's just one lesson-'

'Rin, you shouldn't be jeopardizing your sleep for this. You've taken 3 tests and trained hard all day, you need to rest.'

'We don't have afternoon classes tomorrow. I'll sleep then.'

Sousuke opened his mouth to protest, but then thought better of it.

'I'm going to sleep.' He huffed and began climbing the ladder, pissed off at Momo for disturbing him and then ogling Rin while getting him to teach math for a test he hadn't even bothered studying for and even more pissed off at Rin for being so damn nice to his kouhais when most of them didn't deserve it.

He felt a black rage welling up inside him, ugly jealous tendrils locking around his heart. He glanced again at Momo, who was hugging Rin like his life depended on it. His eyes narrowed in on where he had buried his face in the crook of Rin's neck where the tee had slipped off.

'Rin, your shirt.' He said curtly.

 _My shirt_ , he thought wryly, _just like how Rin is mine. I was friends with him first. I've known him far longer than you. And I love him more than you'll ever be able to. Rin's my lifeline. You think you're special?_ Sousuke gave a sadistic smile in Momo's direction. _You clearly haven't met me yet._

Rin adjusted the shirt, much to Momo's dismay. He smiled up at Sousuke.

'Thanks, Sou.'

Sousuke rolled over in his bunk, turning to face the wall as Rin started explaining injective relations. The rush of warmth still hadn't faded from his face.

That was the problem with Rin. In many ways, he had dealt with things no one of his age should have to deal with. But underneath it all, Rin was still like a child. So astonishingly naïve and trusting, wearing his heart on his sleeve. Giving a part of his soul to everyone he touched. Beautiful on the inside as well as the out.

His purity and romanticism was a part of his allure, and it never failed to draw everyone in. He had a natural magnetism, an aura that was inescapable and bright, almost scorching. His personality was larger than life, and he wielded a field of gravitation so great that everyone in his vicinity was pulled into his paths of orbit, no matter how hard you tried to resist.

Rin was Sousuke's sun.

At one point, he had wondered if he was becoming too attached. Where Rin was giving, Sousuke was selfish. Surely, these kind of emotions were unhealthy? This urge to monopolize all of Rin's time, to have his attention only on himself? To be the person Rin could depend on? To be the person to claim all of Rin's firsts, his heart, his soul, the very fibres of his being?

 _Friends, we're just friends_.

At least, that's what he kept telling himself.

He'd already had years of practice hiding his feelings and thoughts. This would be no different, certainly more difficult to hide, but bottling his emotions seemed a safer alternative to the other, more dangerous option of confessing. He knew he'd scare Rin away – this wasn't a simple crush or fleeting attraction. Sousuke had been in love with Rin for years. The intensity and depth of his feelings couldn't be described. He knew that revealing it prematurely would overwhelm him and possibly frighten him away. Sousuke didn't want that. He wanted to be next to Rin, no matter what kind of companionship that ordained. And there was also the possibility of rejection, something that Sousuke really didn't like to dwell on.

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 **A/N:** Hope you liked it, guys! Read and Review!

Thanks for the follows and favorites from **Shiranai Atsune** and **Alex-shadowed-wolf.** Much appreciated!

 **Reviews for Chapter 1:**

 **QuickSilver: Aw, it's short and sweet!**

 _Thanks babe! Hope this one's to your liking too!_


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